Treating hydrocarbon oils



Patented Apr. 17, 1934 TREATING HYDROOARBON OHJS No Drawing. Application April 21, 1930,

Serial No. 446,176

9 Claims.

This invention relates to treating hydrocarbon oils and more particularly to methods of treating such oils as the lighter fractions of petroleum, such as gasoline, kerosene and the like, whereby the oils are rendered negative to the doctor test.

In its broadest aspect the invention contemplates the method of treating hydrocarbon oils with a solution of an alkali metal hydroxide or carbonate in the presence of free sulphur or an 10 oxidizing agent or both and a contact catalyst consisting of a chemically inert finely divided solid material, whereby the oil, which was previously positive to the doctor test due to the presence of certain sulphur compounds contained therein, may be rendered negative to the doctor test.

Ordinarily the lig ter hydrocarbon oils derived from petroleun, both those fractions obtained by direct distillation without decomposi- .tion and those which may be obtained from the decomposition of higher boiling fractions of petroleum by cracking, contain to a varying degree certain undesirable sulphur compounds whose presence is indicated by a positive reaction to the well-known doctor test. This test consists in shaking a few ounces of the oil to be tested with free sulphur and an aqueous solution of sodium plumbite. After allowing the mixture to settle any discoloration produced in the oil or in the aqueous solution or at the oil-solution interface indicates that the oil contains undesirable sulphur compounds and it is designated as being positive to the doctor test or sour. A corresponding lack of color indicates that the oil is negative to the doctor test or swee In order that oils such as gasoline and kerosene which are positive to the doctor test may be rendered negative thereto and the objectionable sulphur compounds either removed or changed in i composition, it is common practice to treat the oil with a solution of sodium plumbite made by dissolving litharge in an aqueous solution of caustic soda. Free sulphur is usually added to the oil during treatment. In the reaction which takes place, the objectionable sulphur compounds in the oil are eliminated and the oil is rendered negative to the doctor test. The procedure is ordinarily referred to as sweetening the oil.

While the ordinary methods of treating with sodium plumbite solution and sulphur are eifective in rendering the lighter petroleum oils negative to the doctor test, they have the disadvantage of being somewhat expensive due to the fact that, through continued use, the plumbite solution j tends to become spent to the extent that it will fail to sweeten any further oil. When the sodium plumbite solution becomes spent, it must be replaced by a new solution and the cost of such solution is a very appreciable portion of the total cost of refining the oil.

In the practice of the present invention, hydrocarbon oils which are positive to the doctor test are rendered negative thereto by treating, in the substantial absence of any soluble lead salts, with a solution of an alkali metal hydroxide or carbonate, preferably in the presence of free sulphur, although an oxidizing agent such as a peroxide of the alkaline earth metals may also be used, and a contact catalyst consisting of a chemically inert finely divided solid material, which may be, for example, fullers earth, bauxite, activated carbon or the like. Th se materials are known in the art as adsorbents and are referred to in the claims as adsorbent catalysts.

In the application of the invention to the treatment of the lighter distillates of petroleum the procedure may be substantially as follows:

An oil which is positive to the doctor test, as for example, a naphtha having approximately the boiling range of gasoline and derived from cracking heavier and less volatile fractions of a Mid- Continent crude petroleum is treated, in the presence of the desired amount of free sulphur, with a quantity of a reagent consisting of finely divided fullers earth suspended in an aqueous solution of caustic soda.

The treatment of the oil with the reagent is applied, preferably, as a continuous process in a closed system, excluding any contact between the oil and air. For example, the oil may be treated continuously by forcing it through suitable mixing devices, wherein it is thoroughly mixed with the sweetening reagent, after which the mixture of oil and reagent may be introduced into settling tanks of suitable capacity, wherein stratification of the oil and aqueous reagent takes place. The sweetenifig reaction takes place during the contact of the reagent and the oil and the sweetened oil may be separated by decanting from the settling tank, while the reagent is recirculated to the mixing chambers wherein it is mixed with further oil and the treating cycle continued. If desired the reagent which is recirculated may be blown with air prior to its reuse in sweetening oil.

The quantity of free sulphur present during the treating and sweetening operation should be regulated carefully in order to avoid the presence of an excess which might leave free sulphur in the finished oil. The introduction of the sul- 110 phur may be accomplished advantageously by disolving the desired quantity of sulphur, which may be in the proportion of five (5) to ten (10) pounds of sulphur per one thousand (1,000) barrels of oil, in the oil prior to mixing it with the sweetening reagent.

The caustic soda solution in which the catalyst is suspended may, for example, have a concentration of approximately thirty (30) pounds of NaOH per barrel and it is found that the suspension does not sweeten oil at a satisfactory rate if the concentrationof the caustic soda. solution is allowed to fall very much below twenty (20) pounds per barrel. As. the continuous process of sweetening proceeds, additional caustic soda may be added to the suspension from time to time in order that the concentration of the solution may not fall below the desired minimum.

While free sulphur may be employed during sweetening of the oil with caustic'or carbonate solution in the manner described above, ithas been found that certain other materials, particularly the peroxides, perborates, or persulphates of the alkaline earths which yield active oxygen in aqueous solution, and other active oxygen containing compounds such as sodium or potassium permanganate and the. like, may be used instead of, or in addition to, the free sulphur. These oxidizing agents are described in the claims as water-soluble per-oxidizing agents.

Certain of the undesirable sulphur compounds contained in the oil may not be readily acted upon during treatment with the solution of hydroxide or carbonate and a contact catalyst but with available oxygen present, as in the form of the foregoing compounds, these sulphur compounds are readily oxidized or made susceptible totreatment. Thus, for example, it may be advantageous to add sodium peroxide to the caustic solution used in the treating operation and which may be introduced to the extent of 1.75 pounds of sodium peroxide per barrel of solution.

The step of acid treatment of the oil, employing well-known means of treating with sulphurie acid, may be applied prior to the treatment for rendering the oil negative to the doctor test, in which case it may be desirable to wash the oil thoroughly with analkaline solution prior to its treatment with the sweetening reagent in caustic soda solution in order to avoid the undesirable possibility of the acid coming in contact with the caustic suspension. In some instances, for example when the oils contain acidic constituents even though they may have had no prior treatment with sulphuric acid, it may prove desirable to precede the treatment with the sweetening reagent by a treatment with an alkali in order that the oil may be thoroughly free from acidic materials of any kind.

Obviously many modifications and variations of the invention, as hereinbeiore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims. v

We claim:

I; The method of sweetening petroleum distillate oil which comprises treating the oil with a composition of matter consisting of an aqueous alkali, an adsorbent catalyst and free sulphur.

2. The method of sweetening petroleum distillate oil which comprises treating the oil with a compositon of matter consisting of an adsorbent catalyst, a caustic soda solution and free sulphur.

3. The method of sweetening petroleum distillate oil which comprises treating the oil with a composition of matter consisting of an adsorbent catalyst, a soda ash solution and. free sulphur.

4. The method. of sweetening petroleum distillate oilwhich comprises treating the oil with a compositionrof matter consisting of an aqueous alkali, fullers earth and free sulphur.

5. The method of sweetening petroleum distil late oil which comprises treating the oil with a composition of matter consisting of an aqueous alkali, an adsorbent catalyst, in the presence of free sulphur and a water-soluble per-oxidizing agent.

6. The method of sweetening petroleum distillateoil which comprises treating the oil with a composition of matter consisting of an adsorbent. catalyst, a caustic, soda solution, free sulphur and a water-soluble per-oxidizing agent.

7.. The method of sweetening petroleum distillate oil which comprises treating the oil with a composition of matter consisting of an adsorbent catalyst, a caustic soda solution, free sulfur, and sodium peroxide.

8. The method of sweetening petroleum distillate oil which comprises treating the oil with a 120. composition of matter consisting of an adsorbent catalyst, a soda ash solution, free sulfur, and sodium peroxide.

9. The method of sweetening petroleum distillate oil which comprises treating the oil with a composition of matter consisting of fullers earth,

a caustic soda solution, free sulfur, and sodium. peroxide.

' HARRY V. REES.

CHARLES, F. TEICHMANN.

CERTIFICATE OF CORRECTION.

Patent No. 1,955,607. April 17, 1934.

HARRY V. REES, ET AL.

it is hereby certified that error appears in the printed specification of the abeve numbered patent requiring cerreetien as follows: Page 2, line 2, for "diselving" read dissolving; and line 106, claim 5, strike out the words "in the presence of; and that the said Letters Patent should he read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 24th day of July, A. D. 1934,

Bryan M. Battey (Seal) Acting Commissioner of Patents.

CERTIFICATE OF GGRREtJTION.

Patent No. 1,955,607. April 17, 1934.

HARRY V. REES, ET AL.

It is hereby certified that error app-eats in the printed specification of the above numbered patent requiring ccrrecticn as follows: Page 2, line 2, for "disoiving" read dissolving; and line 106, claim 5, strike out the words "in the presence of"; and that the said Letters Patem should be read with these corrections therein that the same may coniorm to the record of the case in the Patent Office.

Signeci and sealed this 24th day of July, A. D. 1934-.

Bryan M. Battey (Seal) Acting Gommissicner of Patents; 

